Explosive cartridges and explosives



Sept. 1963 w. L. GILLILAND 3,103,882

' ExPLosIvE CARTRIDGES AND EXPLOSIVES Filed Jan. 15. 1949 IN VEN TOR.

United States Patent 3,103,882 EXPLOSIVE CARTRIDGES AND EXPLGSIVES William L. Gilliland, 1611 Ferry St, Lafayette, ind. Filed Jan. 15, 1949, Ser. No. 71,137 4 Claims. (Cl. 10224) My invention relates to certain improvements in the form of a device for discharging high explosives to procure a directional effect from the blast with high penetrating power, and to the composition of certain explosives for use in such a device.

These improvements are described under five principal headings relating to the following subjects:

1) A shaped charge with the addition of a void space intended to cause the detonation wave to assume a particular shape before reaching the shaped face whereby the wave movement has a component inwardly toward the longitudinal axis of the mass of explosive and produces explosive forces more fully available in the direction of the blastof the shaped charge. This cartridge is in addition provided with a device for maintaining the liquid explosive under a definite pressure, which can be arranged to reach any desired value of pressure at the proper depth.

(2) An arrangement of explosives in a cartridge of a form that may be similar to the device described in application Serial No. 761,779, filed July 18, 1947, now abandoned, in which two or more explosives of diiferent velocities of detonation are combined in a particular nonhomogeneous arrangement. When detonation is initiated at a selected point in this body of explosive, the detonation wave assumes a particular shape which it does not have in moving through a mass of homogeneous explosive, this shape being produced by the difference in the velocity of the detonation wave in different parts of the explosive mass. The wave shape can be made such as to result in the more rapid passage of the detonation wave along the shaped face of a shaped charge. This in turn results in a blast of greater penetrating power from the shaped change, especially when a metal liner is used on the shaped face. Such an arrangement may also be used with the additional void space described in (1) (3) A means for obtaining from liquid explosives a greater uniformity of action and a more powerful blast than is otherwise attainable. This means consists in filling the cartridge completely full of liquid, without the conventional air space above it, and then, as by means'ot a screw device, placing the explosive under pressure. The pressure control may be facilitated by a flexible accordion-like drum, which yields as the fluid pressure increases, and which compensates for the very slight shrinkage of the rigid case due to hydrostatic pressure.

(4) The components of the liquid explosive mixtures, which are themselves liquids, and which are termed oxygen sources in patent application Serial N 0. 761,780, filed July 18, 1947, now abandoned, as tet-ranitrometh-ane, nirtroform (M.P. 26 C.), tetranitroethylene and trinitro fluoromethane, as Well as the fuel components, also liquids, are degassed prior to mixing by exposing them for a time to ultrasonic vibrations of suitable frequency and intensity. This may be done by immersing a glass flask of such liquid in an oil bath in which a vibrating quartz piezo crystal is maintained. Liquids so treated show a 2 diminished sensitivity to shock, and a more and powerful detonation than before treatment.

(5) A list of suitable explosive substances and combinations for use in the foregoing devices which include some new and some uncommon explosive materials for which new methods of preparation are given in detail. In general, the description in patent application Serial No. 7 61,780 is applicable to the explosives here described, and the mixture of a fuel and an oxygen source in accordance therewith is suggested.

The openation of the explosive cartridge described in (1) above is made clear by the accompanying drawings, in whichr FTGURE 1 is a somewhat diagrammatic representation of one form of cartridge chosen for illustration of some features of this invention.

FIG. 2 is a wave propagation diagram for the structure of FIG. 1.

PEG. 3 is a diagrammatic representation of a two-speed explosive combination indicating wave propagation thereon.

Although the law requires a full and exact description of at least one form of the invention, such as that which follows, it is, of course, the purpose of a patent to cover each new inventive concept therein no matter how it may later be disguised by variations in form or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements or combinations in which the inventive concepts are found.

uniform Explosive Cartridge With Internal Pressure in FIG. 1 a rigid watertight metal container 1, capable of withstanding the external hydrostatic pressures under which it will operate and reasonable internal pressure, is fitted with a suitably constructed head 2 which carries an electric detonator 3 with an insulatedelectric lead 4, the other detonator terminal being grounded. The head 2 is secured to case 1 with an intervening compressible washer by a milled coupler ring 5 (or flat-sided ring) threaded to the case 1 and adjustable to increase or decrease the volume inside container 1. When container 1 is filled with liquid 9, a very small increase or decrease of volume will result in a large increase or decrease of internal pressure. In order that the pressure range may be kept within lower limits than might otherwise be the case, a metal tube 6, with flexible side walls, of an Iaccorcliondike construction, entirely closed and empty or air-filled, is inserted in the space below the detonator 3, so that an increase in pressure is partially compensated by the shrinkage of the volume of this closed metal tube 6.

The principle involved in this feature of internal pressure is simply that of providing a rigid solid container in the form of a metallic shell, and having no air pocket or space in the main path of the detonation wave to :act as a cushion to give any degree of relief to the pressures induced after detonation has begun. While it is true that the container offers very little effective resistance to the detonation pressures after the detonation is under way, and the air cushion latfords essentially no relief to such pressures, nevertheless in the instant of first formation of the detonation wave, and the beginning of the explosive process, these two factors may play a part and it is favorable to greater brisan'ce to have rigid confinement under tension.

Degasified Liquid High Explosives Preferably all liquid explosives used here or elsewhere are degassed. The principle involved is in essence similar to the pressure feature just described. It is desirable to remove the minute air bubbles present in the liquid explosive, and the dissolved gases which may form such bubbles. Since the liquid explosives contemplated for use in this device include the ones described in application Serial No. 761,780, and are essentially tetranitromethane or other oxygen sources, mixed in approximately zero oxygen balance with benzonitrile or other selected fuel substances, it is possible to degassify the liquid oxygen source and the liquid fuel substance separately before mixing. The liquids are simply exposed for a short time to ultrasonic vibrations of a comparatively low frequency, so that the gas evolution takes place. The two liquids are mixed and used as soon as practical afterwards. This procedure results in diminished sensitivity to shock of the mixtures, with consequent greater safety in handling and in im proved penetration by the shaped charge or explosive force in any event when the explosive is fired. It is thus seen that degasified liquid explosives of very high brisance may be provided by this invention.

Annular Wave Source for Shaped Charge The horizontal tube-like portion of case 1 terminates in a void 7, which is formed at least in part by an internal metal shell 8 that excludes the explosive liquid 9 and is given any customary or suitable shape for producing the shaped charge effect. This shell, being fluid tight, maintains a void space between the explosive and the outer end 1th of the cartridge, which is intended to be placed against the casing of the oil well casing (or other object) which is to be perforated. This arrangement is very similar to that described in copending patent application Serial No. 761,779, except for the facilities for producing internal pressure. According to another feature of the present invention a deflector 11 is provided. It may be formed to include a void with walls that are considerably heavier than those intended for producing shaped charge effects, and which in fact serves to obstruct the passage of the detonation wave over the greater part of the cross-sectional area of explosive, permitting it to pass only at the space 12, which space is in the form of a thin ring or annulus, so that the detonation wave passes 12 not as the section of a spherical surface with its center at the point of detonation (detonator 3), but as a ring whose outer diameter is the inner wall of container 1 at the section 12, and whose inner diameter is the outside of metal container 11. The purpose of the obstruction i1 is the creation of a detonation wave of this form. The consequences of this annular detonation wave are shown in PEG. 2.

As seen by reference to wave front 13, which would be annular in form, the wave progressing from annular section 12 would have a component of its movement inwardly toward the longitudinal axis of the tubular portion 14 of casing 11. This would have two advantages. When the wave has no inward component the explosive force tends to spread radially outwardly with considerable dissipation. The inward component minimizes this effect and directs a greater proportion of the explosive force in the desired direction parallel to the longitudinal axis. The other advantage is in connection with the shaped face 16. The unusual effectiveness of such shaped faces appears to be in part due to the sudden impingement of inwardly directed forces emanating from this face. The rapidity with which this effect builds up can be increased by a wave shape which passes more rapidly along the shaped face. If we assume an extreme situation of a wave propagated from a point 18 even with the apex of the shaped face 16, this wave would reach the apex and many other 4, points on the shaped surface somewhat beyond the apex substantially simultaneously. The wave emanating from section 12 is not this extreme but it nevertheless reaches the successive points beyond the apex more quickly after reaching the apex than the spherical waves in prior art shaped charge explosives. The converging of the waves along the center axis as they emanate from the section 12 tends to produce a strong forward component to cooperate with the inwardly directed forces from the shaped face to produce the desired extreme piercing power. The diameter of section :2, its longitudinal spacing from the shaped face, and the shape of the face can be varied to give maximum effects.

Concave Wave Front Obtained by Difierential Explosives A wave shape which maintains adequate forward force along the longitudinal axis and at the same time conforms more closely to the shape of the shaped face will more fully develop the possibilities of the shaped charge effect. This can be accomplished by a non-homogeneous arrangement of explosives having different velocities of their detonation waves, with the explosive detonating more rapidly arranged annularly around that which detonates more slowly. This is illustrated in FIG. 3.

In PEG. 3 an explosive charge, as for a cartridge 1, is represented as including an outer cylinder A of one explosive and a core B of another explosive. They preferably form one rod without a sharp demarkation between them. The outside surface of the rod is essentially pure A while the center is essentially pure B. Such a composition might he obtained by inserting a close-fitting cylinder of compressed B into a tube of compressed A, and then causing a partial fusion of the two and intermingling at the interface by heat. General separation and centering can be maintained by centrifugal force produced by spinning the cylinder about its axis if A is denser than B. For A one may use hexanitromannitol and for B pentaerythritol tetranitrate. In this case heat is applied with extreme caution and not above the point where A becomes fluid. A and B are so chosen that the detonation velocity of A is greater than that of B, with the result that when detonation is initiated the wave 21 that moves along the rod from left to right may start as the usual type of generally spherical wave but progresses to a generally conical or parabolic shape, as suggested in FIG. 3. As a consequence of its concave shape, when wave 21 reaches the metallic conical liner 22 on the shaped face which produces the shaped charge effect, it will pass over the surface of this liner more rapidly than would a flat wave. For example, in the illustration, when the periphery of the wave front moves from a to b, the wave traverses the liner from ct to b. This more rapid passage may result either in a larger portion of the liner metal being present in the high velocity jet and a smaller portion in the slug, or in a higher velocity jet with the consequence that greater penetration is effected by the shaped charge. The actual dimensions of the body of explosive used for this purpose may conform to the interior 9 of the container 1 shown in FIG. 1, and may be employed either with or without the metallic obstruction 11 intended to produce an annular detonation.

The lines 21 are not intended to be exact representations of the wave shapes. Indeed, these may be varied widely by choice of materials and varying degrees and extents of intermingling from the original interface. More than two explosives may be used.

The concave Wave shape may be useful even without the shaped face; and with a flat face (preferably having a liner-like flat plate in contact therewith) may produce results similar to that of a shaped face.

As in H6. 1, it may be desirable, with some explosives at least, to maintain a pressure inside the container, as by a liquid explosive into which the detonator is adjustably projected by turning ring 5. In fact, the solid central core may be omitted if desired and the same liquidexplosive used as explosive B.

Explosives these methods of preparation are of sufiicient importance to warrant, claims are drawn to cover them. The appropriate use and method of employment of each substance is indicated.

The additional substances are:

( 1) The ammonium salt of nitroform as an oxygen source.

(2) The methylammonium salt of nitroform. (3) The diammonium salt of tetranitroethane. (4) Tetranitroethylene.

(5) 2,2,3,3-tetranitrobutanediol-1,4.

(6) 2,2,3,3-tetranitrobutanediol-1,4 'dinitrate. (7) 2,2,2-trinitroethanol.

(8) 1,1,l,2-tetranitroethane.

(9) 2,2,2-trini-troethanol nitrate.

(10) 2,2,Z-trinitroethyldimethylolnitromethane. (11) Dipropargyl.

(12) Nitromalonitrile.

(13) Dinitromalonitrile.

Those which are high explosives suitable, alone, for use in FIG. 1 are (in the above list) 2, 3, 5, 7, 8 and 10.

Those which are suitable for use as oxygen sources as described in my application Serial No. 761,780, in combination with a fuel are 4, 6, 7, 8 and 9. No. 1 might be considered in this class, although it is not as rich in oxygen.

Those which are suitable for fuels as mentioned in the preceding paragraph and more fiully in said application are 11, 12 and 13.

The same numbers are used in the following discussion.

(1) The ammonium salt of nitroform is well-known and is a solid explosive of moderate stability and power, and in. industrial production should be reasonably cheap. It is also an oxygen source.

(2) The methylammonium salt of nitroform is a new composition of matter, produced by the action of methylamine on an equivalent quantity of nitroform in water solution. It is quite soluble in and readily crystallized from water. It is a very powerfiul explosive and its use is highly recommended.

(3) Those compounds containing the 1,1,2,2 tetranitro grouping are generally prepared from the dipotassium salt of tetranitro ethane, and the preparation of this latter substance will be described in detail:

One hundred grams dinitrodibromomethane with or without a solvent, for example 60 m1. methanol, are placed in a 1,000 ml. tall beaker, fitted with a motordriven stirrer and cooled in a salt-ice bath. A solution of 155 gm. potassium cyanide in 230 ml. water is added slowly from a dropping fiunnel, the temperature being maintained below 30 C., in practice between 10 C. and 15 C. in spite of the developed heat. After the addi- 'tion is complete, the mixture is stirred for half an hour, and then filtered through a sintered glass funnel and the precipitate washed with about ml. water. The material is sucked dry on the filter and dried for two hours on a porous plate. It is then dissolved in 250 ml. boiling water to which 0.5 gram potassium carbonate has been previously added, and the resulting solution filtered hot. The clear yellow or amber filtrate is cooled quickly inan ice bath, and the voluminous crystalline precipitate filtered off, washed with a little water and dried. Yield, about 55 grams of the dipotassium salt of 1,1,2,2-tetranitroethane.

In an alternative procedure for forming this substance, 1,2-dinitroethane may be used as a starting material. The disodium salt of 1,2-dinitroethane in water solution, with the theoretical amount of bromine yields an insoluble di bromide. This dibromide is removed and suspended in a 50% solution of methyl alcohol in water, and treated with a water solution of potassium nitrite and potassium cyanide in equivalent quantities. The dipotassium salt of tetranitroethane is formed as described above and is purified intthe same way. in this procedure, chlorine may be used in place of bromine if desired.

If the dipotassium salt of tetranitroethane so prepared is added cautiously, in portions, to a solution of an equivalent quantity of ammonium chloride in anhydrous liquid ammonia, potassium chloride and the diammonium salt of tetranitroethane are formed. The potassium chloride is filtered off, and washed with anhydrous ammonia to extract residual ammonium salt. The ammonium salt so produced is a yellow crystalline solid, and is an explosive of great power. Its use is recommended.

An alternate laboratory method consists in adding aqueous ammonium chloride in equivalent amount to the disilver salt of tetranitroethane, when the insoluble 'silver chloride which is formed may be filtered oil, and

the diammonium salt recovered by evaporation.

(4) Tetranitroethylene may be conveniently prepared by the electrolysis of the water solution of the dipotasslum salt of tetranitroethane, forming in oily drops at the anode.

It may be readily prepared from the disilver salt of tetranitroethane by adding any reagent that has a marked aflinity for silver. For example, by grinding the silver salt with metallic mercury, or with mercuric chloride, or with stannous chloride when silver chloride and mercurous chloride or tin is formed. A simple method of preparation is the grinding together of equivalent quantities of dry mercuric chloride and the dry silver salt or" tetranitroethane until a very intimate mixture is secured and then removing the oil by slow distillation in vacuo. Tetranitroethylene is a colorless, slowly volatile oil with a characteristic musk-like odor.

One-half of its oxygen content is available to burn other fuel substances and its use is suggested and recommended -as an oxygen source in the sense that this term is used in application Serial No. 761,780. The fuel substances with which it may be mixed as an oxygen source are the organic compounds which are soluble in tetranitroethylene and which are ordinarily burnable in air. It is also suggested for use to be added to any high explosive to bring the resulting explosive mixture toward zero oxygen balance so as to produce a much more powerful and bristant product.

(5) If 10 grams of the finely powdered dipotassium salt of tetranitroethane be added slowly to a mixture of 8 ml. 40% aqueous formaldehyde, 8 ml. water and 10 ml. of phosphoric acid, at temperatures below 0 C., and if the reaction is properly initiated at the begin ning of the addition, 2,2,3,3-tetranitr0butanediol-1,4 is

produced. This substance is an excellent explosive.

(6) If the diol just described is slowly added to nitric acid (1.52 density) or to a nitric-sulphuric acid mixture, at temperatures of 0 C. to 10 C., the dinitrate' is produced. This may be used either as an explosive or as an oxygen source.

(7) If 10 grams of potassium nitroform he added slowly to a mixture of 8 ml. 40% aqueous formaldehyde, 8 ml. water and 10 ml. 85% phosphoric acid, at temperatures between 10 C. and 20 C., an oily layer separates which is 2,2,2-trinitroethanol. Upon dewatering (as by pumping) large crystals of this substance separate. It is an excellent explosive and may be used as any oxygen source also.

(8)If 2,2,2-tninitroethanol is treated with phosphorous trichloride or tribromide, a chloride or bromide results. If this chloride or bromide is treated with silver nitrite, or more simply with an aqueous solution of potassium cyanide and potassium nitrite, the potassium salt of l,1,1,2- tetranitroethane is formed. The pure 1,1, 1,2-tetranitroethane may be liberated from this salt with phosphoric acid. It is an explosive but more useful as an oxygen source.

(9) If 2,2,2-trinitroethanol is treated with nitric acid of density 1.52, or with a mixture of nitric and sulphuric acids, with cooling to C. there is produced a nitrate. This nitrate may be used as an oxygen source in combination with fuel materials or in combination with other oxygen sources and fuel materials.

(10) If 10 grams of 1,1,1,2-tetranitroethane is slowly added to 10 ml. of 40% aqueous formaldehyde with stirring and cooling the diol of the structure 2,2,2-trinitroethyldimethylolnitromethane is produced. This is an explosive compound.

(11) D'ipropargyl, C H an isomer of benzene, is a well-known substance, described adequately in the chemical literature. It is recommended as a fuel substance for combination with oxygen sources to produce explosive materials.

(12) if potassium fulminurate is mixed intimately with an excess of phosphorous pentoxide, and allowed to stand 24 hours, there may be distilled from the mixture under reduced pressure nitromalonitrile, which is a useful fuel substance, particularly when mixed with substances containing a percentage content of oxygen greater than that of nitroma lon'itrile, such as trinitroaeetonitrile, nitroform or tetranitroethylene.

(13) Nitromalonitrile produced as indicated may be nitrated with nitric acid of a density of 1.52 or with nitric and sulphuric acid to form dinitromalonitrile, which is an explosive. As in the case of nitromalonitrile, that dinitromalonitrile may be mixed with trinitroacetonitrile nitroform or tetranitroethylene, or other substance containing a percentage content of oxygen higher than nitromalonitrile to produce an explosive of very great power.

In connection with the above explosive mixtures, and more particularly with the mixtures described in application Serial No. 761,780, it is frequently desirable to use tetranitromethane as an oxygen source. This material is frequently prepared by some operators in an impure and dangerous state. It may be brought to a high state of purity and stability by means of nitric acid. The followinw is a specific example of a procedure for such purification.

One kilogram of freshly prepared tetranitromethane is poured into one kilogram of pure nitric acid having a density of 1.50 or higher. It dissolves at once with a cooling of the mixture. The resultant solution is allowed to stand for at least a day and preferably longer, and is then poured into very clean ice and water, and the dense layer of tetranitromethane separated and washed thoroughly with water. It is then dried with anhydrous magnesium sulphate and filtered through a sintered glass funnel.

This same method of nitric acid treatment is useful in cleaning up any contaminated aliphatic-nitro compound that does not react with nitric acid. in the case of products from the Victor Meyer synthesis, it is most useful in removing nitrites and other undesirable side reaction products. Nitroethane, dinitroethane and numerous other compounds may be purified by this procedure.

lclaim:

1. A shaped explosive cartridge including a body of explosive having a concave shaped face, a detonator disposed reanvardly of said face and extending into the explosive in a position for detonating the explosive and a centered obstruction between the detonator and said face embedded in the explosive and of smaller outside diameter than the outside diameter of the explosive body where it is embedded to obstruct the center portion of the detonation wave and leaving a peripheral generally annular passage of communication past said obstruction to cause the Wave passing it to emanate from an annular zone, said obstruction comprising a hollow member having its wall furthest from the shaped face considerably heavier than a shaped face liner to prevent the passage through it of a force which would detonote the explosive in front of it.

2. A shaped explosive cartridge including a body of explosive having a concave shaped face, a detonator disposed rearwardly of said face and extending into the explosive in a position for detonating the explosive and a centered obstruction between the detonator and said face embedded in the explosive and of smaller outside diameter than the outside diameter of the explosive body where it is embedded to obstruct the center portion of the detonation wave and leaving a peripheral generally annular passage of communication past said obstruction to cause the wave passing it to emanate from an annular zone, said obstruction comprising a hollow member having its wall furthest from the shaped face considerably heavier than a shaped face liner to prevent the passage through it of a force which would detonate the explosive in front of it, and means between the detonator and the obstruction for confining the detonation wave as it approaches the obstruction to a centered zone thereof substantially narrower than the diameter of the obstruction to reduce the tendency of the detonation wave to collapse the obstruction radially with a shaped face effect.

3. A shaped explosive cartridge including a body of explosive having a concave shaped face, a detonator disposed rearwardly of said face and extending into the explosive in a position for detonating the explosive and a centered imperforate and generally circular obstruction extending to the peripheral zone of the body between the detonator and said face embedded in the explosive and of smaller outside diameter than the outside diameter of the explosive body where it is embedded to obstruct the center portion of the detonation wave and leaving a peripheral generally annular passage of communication past said obstruction to cause the wave passing it to emanate from an annular zone, said obstruction comprising a hollow member having its wall furthest from the shaped face considerably heavier than a shaped face liner to prevent the passage through it of a force which would detonate the explosive in front of it.

4. The combination of a detonator and an explosive charge arranged to be detonated thereby and having an initiating portion and a main portion, the main portion extending along an axis from the initiating portion and terminating on its end opposite the initiating portion in a shaped face directed along said axis; said initiating portion detonating the main portion simultaneously substantially all around the periphery of the main portion at the end thereof opposite the shaped face and in that peripheral zone only, and being substantially cup-shaped, means for insulating said initiating portion from the main portion, except at the peripheral zone, as to transmission of detonation, and said initiating portion being connected to the detonating area of the detonator by a zone substantially on said axis and substantially narrower in cross section than the rim of the hollow of the cup-shaped portion to reduce the tendency of the face thereof to function with a shaped face effect.

References Cited in the file of this patent UNITED STATES PATENTS 94,813 Dickey Sept. 14, 1869 939,886 Wolsey Nov. 9, 1909 1,231,451 Swoboda June 26, 1917 1,406,844 Gelm Feb. 14, 1922 (tithes references on foiiowiug page) UNITED STATES PATENTS 10 Coe Mar. 29, 1949 Lawrence Dec. 23, 1952 Iasse Feb. 17, 1953 FOREIGN PATENTS Great Britain Oct. 12, 1948 OTHER REFERENCES An article on the brisanrt action of explosives by Sukharevsky, from a Russian publication entitled Tekhnika 1' Snabzhenie Krasnoi Annii, vol. 170, pages 13-18 and vol. 177, pages 13-418 (published in 1925). Copy in Div. 70. Div. 70.

There is also an unoificial translation in UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Now $103,882 September 17, 1963 William L Gilliland It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line '73, for "any" read an column 7, line 1'7, for "cooling the" read colling, the

Signed and sealed this 21st day of April 1964.,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J BRENNER Attesting Officer Commissioner of Patents 

1. A SHAPED EXPLOSIVE CARTRIDGE INCLUDING A BODY OF EXPLOSIVE HAVING A CONCAVE "SHAPED" FACE, A DETONATOR DISPOSED REARWARDLY OF SAID FACE AND EXTENDING INTO THE EXPLOSIVE IN A POSITION FOR DETONATING THE EXPLOSIVE AND A CENTERED OBSTRUCTION BETWEEN THE DETONATOR AND SAID FACE EMBEDDED IN THE EXPLOSIVE AND OF SMALLER OUTSIDE DIAMETER THAN THE OUTSIDE DIAMETER OF THE EXPLOSIVE BODY WHERE IT IS EMBEDDED TO OBSTRUCT THE CENTER PORTION OF THE DETONATION WAVE AND LEAVING A PERIPHERAL GENERALLY ANNULAR PASSAGE OF COMMUNICATION PAST SAID OBSTRUCTION TO CAUSE THE WAVE PASSING IT TO EMANATE FROM AN ANNULAR ZONE, SAID OBSTRUCTION COMPRISING A HOLLOW MEMBER HAVING ITS WALL FURTHEST FROM THE "SHAPED" FACE CONSIDERABLY HEAVIER THAN A "SHAPED" FACE LINER TO PREVENT THE PASSAGE THROUGH IT OF A FORCE WHICH WOULD DETONATE THE EXPLOSIVE IN FRONT OF IT. 